AB0058 NOVEL BIOMARKERS FROM THE S100 PROTEIN FAMILY OF RHEUMATOID ARTHRITIS PROGRESSION WHICH CAN BE REGULATED BY EPIGENETIC DRUGS
Authors: L. Roszkowski, B. Jaszczyk, M. Ciechomska
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Monocytes are key players in initiating and maintaining inflammation by producing proinflammatory cytokines and S100 proteins in rheumatoid arthritis (RA). Several studies demonstrated that epigenetic drugs affecting DNA methylation can modulate the production of proinflammatory mediators. <h3>Objectives</h3> This study aimed to test specific DNA methylation inhibitor (RG108) and activator (budesonide) in the regulation of proinflammatory cytokines and S100 proteins in RA monocytes. Our study also looked for new and better biomarkers of high disease activity in RA patients. <h3>Methods</h3> RNA sequencing (RNA-seq) analysis of healthy controls (HC) and RA monocytes was performed. Cell viability was determined in THP-1 monocytic cell line following RG108 and budesonide treatment. Pro- and anti-inflammatory genes such as the S100 family, TNF, IL-8 were validated by qRT-PCR following DNA methylation-targeted drug treatment. The concentrations of proteins from the S100 family in serum and synovial fluid were tested with ELISA assays and their correlation with clinical parameters was carried out. <h3>Results</h3> Based on the RNA-seq analysis, RA monocytes had significantly increased levels of S100A8 (2,2-fold, p=0,024), S100A9 (1,9-fold, p=0,017), S100A11 (1,2-fold, p=0,007), S100A12 (1,6-fold, p=0,007), MYD88 (1,2-fold, p=0,008), JAK3 (1,8-fold, p=0,009), IQGAP1 (1,4-fold, p=0,02), and decreased level of IL10RA (0,7-fold, p=0,011), TGIF1 (0,3-fold, p=0,046) transcripts. In addition, stimulation of THP-1 cells with budesonide (DNA methylation activator) statistically reduced expression of S100A8 (3,0-fold, p= 0,0390), S100A9 (4,4-fold, p= 0,0317), S100A12 (3,3-fold, p= 0,0260), IL-8 (6,8-fold, p= 0,0286) and TNF (7,5-fold, p= 0,0260) genes. In contrast, THP-1 monocytic cell line treated with RG108 (DNA methylation inhibitor) had an increased level of S100 family (S100A8, -A9, -A11, -A12) and TNF genes. ELISAs analysis also revealed significant increased levels of S100A8 (p = 0.0116), S100A11 (p = 0.0138), and S100A12 (p = 0.0296) proteins in RA patients compared to HC sera, similar in early RA sera compared to HC S100A8 (p = 0.0024), S100A11 (p = 0.0020) and S100A12 (p = 0.0059). Moreover, protein levels of S100A8 (p=0.0005), S100A11 (p=0.0007) and S100A12 (p=0.0005) in the synovial fluid of advanced RA patients compared to HC serum were significantly elevated. All these data suggest that a protein of the S100 family may be a promising biomarker of RA progression. In ROC analyses, serum levels of S100A8 and S100A12 proteins were more specific {area under the curve (AUC)=0.78, p=0.006 and AUC=0.87, p=0.0006} respectively in RA patients than CRP levels. In addition, results indicate that S100A8 and S100A12 can serve as a better biomarker of high disease activity than CRP levels. <h3>Conclusion</h3> We have demonstrated that S100 family proteins are increased in RA monocytes (transcriptomics) similar to enhanced S100 production in sera and synovial fluids (ELISA) in RA patients. Our data suggest that the proteins S100A8 and S100A12 in particular are strongly increased during ongoing inflammation, so they could be used as a better biomarker of disease activity than CRP. Interestingly, S100 proteins can be regulated by epigenetic drugs, suggesting their potential use in the targeting of RA inflammation. <h3>Acknowledgements</h3> This work was supported by a grant from National Science Centre (2018/30/E/NZ5/00104). <h3>Disclosure of Interests</h3> None Declared.